Remove KProbe logic from Drainer

[nader-ziada]

/area networking

Follow up from Serving PR: knative/serving#12033

• comment about KProbe logic in drainer being a duplicate functionality user pkg drain for draining in queue proxy serving#12033 (review)

A related concern (but I don't think it should block this PR) is why the drainer has KProbe logic in it
https://github.com/knative/pkg/blob/main/network/handlers/drain.go#L157

I think that makes the network.NewProbeHandler a noop in this instance
https://github.com/knative/networking/blob/main/pkg/probe_handler.go#L37

• Other comment about same user pkg drain for draining in queue proxy serving#12033 (comment)

[dprotaso]

cc @runzexia who included the KProbe logic in the drainer - is there a reason you couldn't consume the handler from knative.dev/networking ?

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[pierDipi]

/remove-lifecycle stale

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[dprotaso]

/lifecycle frozen